Now the rebound continues with Micron beating Samsung to the punch, becoming the first to release commercial phase-change memory (PCM).

Phase-change memory is a new kind of storage chip, which offers a superior alternative to the tradition silicon-based NAND flash storage. PCM is built on chalcogenide glass -- glass that contains one or more of the chalcogenide (sulfur, selenium or tellurium) elements. When heated, the glass switches from crystalline to amorphous, altering electrical properties. Modern PRAM also adds two intermediate states, making for four-states per cell.

Micron's phase-change memory will no doubt be pricey, but it promises high volume and a slew of benefits. It boasts that the memory will cut smartphone boot times, improve application response times (by cutting latency), and even yield small power savings. The memory is not a major power consumer, so these gains likely will amount to minutes of extra battery life, not hours.

Micron's phase-change memory is incorporated into a 2-chip design, which incorporates both LPDDR2 volatile memory and PCM non-volatile memory.

Micron is offering its PCM as an all-in-one volatile/non-volatile solution, solution that includes a 1-gigabit PCM chip attached to a 512-Mbit LPDDR2 chip, connected by a custom interface inside a single package.

Tom Eby, Vice President of the Wireless Solutions Group at Micron comments, "Our commitment to innovation and continued development of advanced products to address the voracious demands of the wireless industry is clear and strong. We are determined to evolve and innovate by continuing to offer the best-tailored solutions for both today's and tomorrow's market requirements."

The new memory will be built on a 45 nm process.

II. Other Solutions Near Market

The only other driving concern (other than price) when it comes to PCM is sensitivity to temperature. Given the high temperatures found in many mobile devices, Micron's solution will likely face a tough test to see whether it has worked out these kinks.

Micron may be the first to take the technology commercial, but it's hardly the first to experiment with PCM. Intel Corp. (INTC), International Business Machines, Inc. (IBM), and Samsung have all sampled PCM chips in recent years. Phase-change memory is based on the so-called "Ovshinsky effect", a property for quantified and patented by physicist Stanley Ovshinsky in the mid-1960s.

PCM is built using chalcogenide glass -- a special type of doped glass.
[Image Source: Univ. of Southampton]

quote: Glass is amorphous by definition, if it switches to crystalline it's no longer glass.

That's not quite correct, either, if I understand my physics. Crystallinity is measured over short (a few atoms' worth) and long distances. Amorphous solids have short-range crystallinity, resulting in increased hardness and density when compared to liquids and gases.

A common misconception is the glass in PCM changes state (solid, liquid, gas or plasma). It remains a solid, and instead changes phase, which, as a gross oversimplification, is a subset of a state. Hence, the name phase-change memory, not state-change memory.

quote: One cannot patent "Ovshinsky Effect" nor more than he or she can patent melting of water ice; physical processes are not patentable, means of achieving them are.

Correct, the effect was not patented. The method of achieving the effect was, which does not occur naturally. He patented his process and particular set of conditions (there are others).